This expanding planter, Graine de Pot, is the design of Francois Clerc. The design responds to the needs of urban gardeners with limited space for storing pots in the off-season and is made from a biodegradable plastic that is safe for composting when the pot is no longer needed...

While the minimal explanation of the design on Clerc's site leaves a lot of questions unanswered, the idea of temporary planting vessels is one that could be further explored. Via:Core77.